U.S. patent application number 12/339326 was filed with the patent office on 2009-04-23 for golf club with optimum moments of inertia in the vertical and hosel axes.
Invention is credited to Noah De La Cruz, Charles E. Golden, John W. Morin.
Application Number | 20090105010 12/339326 |
Document ID | / |
Family ID | 40564015 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090105010 |
Kind Code |
A1 |
De La Cruz; Noah ; et
al. |
April 23, 2009 |
GOLF CLUB WITH OPTIMUM MOMENTS OF INERTIA IN THE VERTICAL AND HOSEL
AXES
Abstract
A golf club is provided having a hollow body golf club head
comprising discrete concentrations of weight or mass located away
from the center of gravity or the geometric center of the club head
to optimize the moment of inertia of the club head about both the
vertical axis running through the center of gravity or geometric
center of the club head, hereinafter referred to as the "y-axis,"
and the axis running through the center of the shaft of the golf
club, hereinafter referred to as the "hosel axis." The ratio of
moment of inertia of the club head about the y-axis to moment of
inertia of the club head about the hosel axis is preferably 0.55.
More preferably, this ratio is 0.75.
Inventors: |
De La Cruz; Noah; (Carlsbad,
CA) ; Golden; Charles E.; (Carlsbad, CA) ;
Morin; John W.; (Carlsbad, CA) |
Correspondence
Address: |
ACUSHNET COMPANY
333 BRIDGE STREET, P. O. BOX 965
FAIRHAVEN
MA
02719
US
|
Family ID: |
40564015 |
Appl. No.: |
12/339326 |
Filed: |
December 19, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11552729 |
Oct 25, 2006 |
7497789 |
|
|
12339326 |
|
|
|
|
Current U.S.
Class: |
473/345 ;
473/282; 473/349 |
Current CPC
Class: |
A63B 53/04 20130101;
A63B 2053/0491 20130101; A63B 2209/023 20130101; A63B 53/0466
20130101; A63B 2209/02 20130101; A63B 53/0412 20200801; A63B
53/0408 20200801; A63B 60/02 20151001; A63B 53/0433 20200801 |
Class at
Publication: |
473/345 ;
473/282; 473/349 |
International
Class: |
A63B 53/04 20060101
A63B053/04 |
Claims
1. A golf club comprising a shaft and a club head, wherein the club
head comprises a y-axis running the in the vertical direction
through the geometric center of the golf club head and a hosel axis
running parallel to the center of the shaft and through a hosel
base, wherein the ratio of the MOI(y-axis) to the MOI(hosel axis)
is greater than about 0.55.
2. The golf club head of claim 1, wherein the MOI(hosel axis) is
equal to or less than about 800 kgmm.sup.2.
3. The golf club head of claim 2, wherein the MOI(hosel axis) is
equal to or less than about 710 kgmm.sup.2.
4. The golf club head of claim 2, wherein the MOI(y-axis) is equal
to or greater than about 450 kgmm.sup.2.
5. The golf club head of claim 2, wherein the MOI(y-axis) is equal
to or greater than about 470 kgmm.sup.2.
6. The golf club of claim 1, wherein the ratio of the MOI(y-axis)
to the MOI(hosel axis) is greater than about 0.75.
7. The golf club of claim 6, wherein the ratio of the MOI(y-axis)
to the MOI(hosel axis) is greater than about 1.0.
8. The golf club of claim 1, wherein the volume of the club head is
between about 390 cc and about 420 cc.
9 The golf club of claim 1, wherein the volume of the club head is
between about 350 cc and about 460 cc.
10. The golf club of claim 1, wherein the MOI(y-axis) is between
about 470 kgmm.sup.2 and about 600 kgmm.sup.2 and wherein the
MOI(hosel axis) is between about 600 kgmm.sup.2 and about 725
kgmm.sup.2.
11. The golf club of claim 1, wherein the MOI(y-axis) is between
about 545 kgmm.sup.2 and about 600 kgmm.sup.2 and wherein the
MOI(hosel axis) is between about 600 kgmm.sup.2 and about 725
kgmm.sup.2.
12. The golf club of claim 1, wherein ratio of the MOI(y-axis) to
the volume of the club head is greater than about 0.90
kgmm.sup.2/cm.sup.3.
13. The golf club of claim 12, wherein ratio of the MOI(y-axis) to
the volume of the club head is greater than about 1.0.
kgmm.sup.2/cm.sup.3.
14. The golf club of claim 13, wherein ratio of the MOI(y-axis) to
the volume of the club head is greater than about 1.10
kgmm.sup.2/cm.sup.3.
15 The golf club of claim 1, wherein the golf club is constructed
from multiple materials
16. The golf club of claim 1, wherein said club head comprises a
face, crown, skirt, hosel and sole, wherein the sole comprises at
least a first and a second weight member and a hosel base, wherein
a first weight member is located toward the face edge of the sole
and is proximate the hosel base, and wherein the first and second
weight members have a higher density than the sole or have a
greater thickness than the sole to increase the moment of inertia
of the club head.
17. The golf club of claim 16, wherein the second weight member is
located toward the back and toe edge of the sole.
18. The golf club of claim 16, wherein the second weight member is
located toward the face and toe edge of the sole.
19. The golf club of claim 16, wherein the second weight member is
located adjacent to and runs substantially along the entire length
of the back edge of the sole.
20. The golf club of claim 16, wherein the first weight member runs
substantially along the entire length of the face edge of the sole
and wherein the second weight member is located adjacent to and
runs substantially along the entire length of the back edge of the
sole.
21. The golf club of claim 20, further comprising a third weight
member disposed on the sole between the first and second weight
members.
22. A golf club comprising a shaft and a club head, wherein the
club head comprises a y-axis running the in the vertical direction
through the geometric center of the golf club head and a hosel axis
running parallel to the center of the shaft and through a hosel
base, wherein the club head has a volume greater than about 350 cc
and wherein the ratio of the MOI(y-axis) to the volume of the club
head is greater than about 0.90 kgmm.sup.2/cm.sup.3.
23. The golf club of claim 22, wherein the MOI(hosel axis) is equal
to or less than about 800 Kgmm.sup.2.
24 The golf club of claim 23, wherein the MOI(hosel axis) is equal
to or less than about 710 Kgmm.sup.2.
25. The golf club of claim 23, wherein the MOI(y-axis) is equal to
or greater than about 450 Kgmm.sup.2.
26 The golf club head of claim 25, wherein the MOI(y-axis) is equal
to or greater than about 470 kgmm.sup.2.
27. The golf club of claim 22, wherein the ratio of the MOI(y-axis)
to the MOI(hosel axis) is greater than about 0.55.
28. The golf club of claim 22, wherein the ratio of the MOI(y-axis)
to the MOI(hosel axis) is greater than about 0.75.
29. The golf club of claim 22, wherein the ratio of the MOI(y-axis)
to the volume of the club head is between about 0.9
kgmm.sup.2/cm.sup.3 and about 1.30 kgmm.sup.2/cm.sup.3.
30. The golf club of claim 22, wherein the golf club is constructed
from multiple materials.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. application Ser. No. 11/552,729, filed on Oct. 25, 2006, which
is incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to golf clubs, and more particularly,
to metal wood and utility-type golf clubs having improved mass
characteristics.
BACKGROUND OF THE INVENTION
[0003] The complexities of golf club design are known. The
specifications for each component of the club (i.e., the club head,
shaft, grip, and subcomponents thereof) directly impact the
performance of the club. Thus, by varying the design
specifications, a golf club can be tailored to have specific
performance characteristics.
[0004] The design of club heads has long been studied. Among the
more prominent considerations in club head design are loft, lie,
face angle, horizontal face bulge, vertical face roll, center of
gravity location, rotational moment of inertia, material selection,
and overall head weight. While this basic set of criteria is
generally the focus of golf club designers, several other design
aspects must also be addressed. The interior design of the club
head may be tailored to achieve particular characteristics, such as
the inclusion of a hosel or a shaft attachment means, perimeter
weights on the club head, and fillers within the hollow club
heads.
[0005] Golf club heads must also be strong to withstand the
stresses that occur during repeated collisions between the golf
club and the golf balls. The loading that occurs during this
transient event can create a peak force of over 2,000 lbs. Thus, a
major challenge is to design the club face and club body to resist
permanent deformation or fracture. Conventional hollow metal wood
drivers made from titanium typically have a uniform face thickness
exceeding 2.5 mm or 0.10 inch to ensure structural integrity of the
club head.
[0006] Players generally seek a metal wood driver and golf ball
combination that delivers maximum distance and landing accuracy.
The distance a ball travels after impact is dictated by the
magnitude and direction of the ball's initial velocity and the
ball's rotational velocity or spin. Environmental conditions,
including atmospheric pressure, humidity, temperature, and wind
speed, further influence the ball's flight. However, these
environmental effects are beyond the control of the golf equipment
designers. Golf ball landing accuracy is driven by a number of
factors as well. Some of these factors are attributed to club head
design, such as center of gravity and moment of inertia.
[0007] The current trend in golf club manufacturing is to produce
large volume club heads in order to maximize the moment of inertia
of the club head. Concerned that improvements to golf equipment may
render the game less challenging, the United States Golf
Association (USGA), the governing body for the rules of golf in the
United States, has specifications for the performance of golf
equipment. These performance specifications dictate the size and
weight of a conforming golf ball or a conforming golf club. USGA
rules limit a number of parameters for drivers. For example, the
volume of drivers has been limited to 460.+-.10 cubic centimeters.
The length of the shaft, except for putters, has been capped at 48
inches. The driver club heads must fit inside a 5-inch square and
the height from the sole to the crown cannot exceed 2.8 inches. The
USGA has further limited the coefficient of restitution of the
impact between a driver and a golf ball to 0.830.
[0008] The USGA has also observed that the rotational moment of
inertia of drivers, or the Club's resistance to twisting on
off-center hits, has tripled from about 1990 to 2005, which
coincides with the introduction of oversize drivers. Since drivers
with higher rotational moment of inertia are more forgiving on
off-center hits, the USGA was concerned that further increases in
the club head's inertia may reduce the challenge of the game, and
instituted in 2006 a limit on the moment of inertia for drivers at
5900 gcm.sup.2.+-.100 gcm.sup.2 (590 kg mm.sup.2+10 kgmm.sup.2) or
32.259 ozin.sup.2.+-.0.547 ozin.sup.2.
[0009] The USGA limits moment of inertia for drivers, as the
calculated moment of inertia with respect to a vertical axis
through the center of gravity of the club head. Larger MOIs about
the vertical axis preserve more ball speed on off-center impacts.
However, when a golf club head approaches a golf ball during the
downswing the golf club head rotates around the shaft or hosel of
the club. The moment of inertia around this "hosel axis" tends to
be significantly larger than the moment of inertia around the
vertical axis through the center of gravity. The moment of inertia
about the hosel or shaft axis is the rotational mass or "foot
print" of the club that the golfer must work to overcome just prior
to impact in order to hit a straight shot. In large-volume drivers
manufactured to have large moments of inertia around the vertical
axis, this difference in moment of inertia is even more
exaggerated. Players may find it difficult to control a club head
having a very large moment of inertia around the hosel axis,
because it requires more work during the downswing to "square" the
face and hit straight shots.
[0010] Though methods of optimizing the mass properties of golf
club heads exist, there remains a need in the art for a golf club
head having a smaller volume or footprint, and/or an optimized
moment of inertia with respect to the hosel axis or rotational
footprint. Further, there remains a need in the art for a golf club
head having a large moment of inertia around the vertical axis
through the center of gravity and a smaller moment of inertia
around the hosel axis relative to the moment of inertia about the
hosel axis of large volume drivers.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to a hollow body golf club
head having discrete concentrations of weight or mass located away
from the center of gravity or the geometric center of the club head
to optimize the moment of inertia (MOI) of the club head about both
the vertical axis running through the center of gravity or
geometric center of the club head, hereinafter referred to as the
"y-axis," and the axis running through the center of the shaft of
the golf club, hereinafter referred to as the "hosel axis."
[0012] The present invention is generally directed to reducing the
foot print of the club head or to optimize the MOI (y-axis) with
respect to the MOI (hosel-axis). In one aspect, the footprint can
be reduced by lowering the volume of the club head. In another
aspect, the MOI (hosel axis) of the club head can be reduced to
minimize the rotational footprint of the club head without reducing
the volume of the club head.
[0013] A golf club head of the present invention preferably has a
MOI about the y-axis between about 470 kgmm.sup.2 and about 600
kgmm.sup.2 and MOI about the hosel axis between about 600
kgmm.sup.2 and about 725 kgmm.sup.2.
[0014] According to an embodiment of the invention, the ratio of
MOI(y-axis) to MOI(hosel axis) is preferably greater than about
0.55. More preferably, this ratio is greater than about 0.75. In
certain embodiments, this ratio is greater than about 1.00, which
means that advantageously MOI(hosel axis) can be lower than
MOI(y-axis).
[0015] A golf club head according to this invention preferably has
a volume between about 390 cc and about 420 cc to have a smaller
rotational footprint about the hosel axis. When the golf club is
made from multiple materials including plastics, the volume can be
as high as 460 cc. The ratio of MOI(y-axis) to volume of the club
head is preferably greater than about 0.90 Kgmm.sup.2/cm.sup.3.
Preferably, this ratio is preferably greater than about 1.00
kgmm.sup.2/cm.sup.3 and more preferably greater than about 1.10
kgmm.sup.2/cm.sup.3 for a club head having a volume greater than
350 cc. Preferably, this ratio is less than about 1.70
kgmm.sup.2/cm.sup.3. The golf club head of the present invention
may comprise discrete weight members on the sole to increase MOI
and to achieve the above-discussed mass characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a graph showing the preferred ranges of moment of
inertia about a y-axis and about a hosel axis for golf club heads
of the present invention;
[0017] FIGS. 2, 4, 6, 8 and 10 are bottom plan views of idealized
golf club heads of the present invention;
[0018] FIGS. 3, 5, 7, 9 and 11 are bottom plan views of golf club
heads according to the present invention;
[0019] FIG. 12A is a top perspective view of a multi-material
driver club of the present invention; FIG. 12B is similar to FIG.
12A with portions removed for better clarity; FIG. 12C is the
bottom perspective view of the club head of FIG. 12A; FIG. 12D is
the bottom perspective view of the club head of FIG. 12B;
[0020] FIG. 13 is a top plan view of a golf club head of the
present invention; and
[0021] FIG. 14 is a cross-sectional view of a golf club head of the
present invention.
DETAILED DESCRIPTION
[0022] Rotational moment of inertia ("MOI" or "inertia") in golf
clubs is well known in the art, and is fully discussed in a number
of references, including U.S. Pat. No. 4,420,156, which is
incorporated herein by reference in its entirety. When the inertia
is too low, the club head tends to rotate excessively from
off-center hits. A golf club head having a higher moment of inertia
will resist rotation due to an off-center impact between the club
face and a golf ball, thereby reducing loss of ball speed,
mitigating the tendency for the ball to hook or slice and
increasing flight distance and subsequently landing accuracy. The
present invention is directed to a hollow body golf club head
having a hosel, face, crown, skirt and sole, wherein the club head
further comprises discrete concentrations of weight or mass located
away from the center of gravity or the geometric center of the club
head to optimize the moment of inertia (MOI) of the club head about
both the vertical axis running through the center of gravity or
geometric center of the club head, hereinafter referred to as the
"y-axis," and the axis running through the center of the shaft of
the golf club, hereinafter referred to as the "hosel axis." In
particular, the present invention is directed to a metal-wood or
utility golf club head having the above-described mass
characteristics.
[0023] Current driver clubs have a volume of up to the USGA limit
of 460 cc. Higher volume can lead to higher MOI (hosel axis), which
demands more work from the golfer to control the club, such that
the face is perpendicular to the target line at impact. Lowering
the MOI(hosel axis) would reduce the physical demands on the
golfer, while maintaining a high MOI(y-axis) would maintain the
desirable forgiveness in ball speed reduction for off-center
hits.
[0024] The golf club head of the present invention preferably has a
volume between about 390 cc and about 420 cc. The inventor of the
present invention has determined that the MOI(y-axis) is preferably
between about 450 kgmm.sup.2 to about 600 kgmm.sup.2 and more
preferably between about 470 kgmm.sup.2 and about 600 kgmm.sup.2.
The MOI(y-axis) can further be between about 545 kgmm.sup.2 and
about 600 kgmm.sup.2. The MOI(hosel axis) is preferably between
about 600 kgmm.sup.2 and 800 kgmm.sup.2 and more preferably between
about 600 kgmm.sup.2 and about 725 kgmm.sup.2. The shaded area of
the graph of FIG. 1 shows the preferred range and the broken lines
within the shaded area show the more preferred range of MOI values
about both the y-axis and the hosel axis for golf club heads of the
present invention. These preferred MOI(y-axis) and MOI(hosel axis)
values represent less physical demands on the golfer during impacts
with golf balls and maintaining desirable forgiveness in ball speed
reduction for off-center hits. The golf club head preferably has a
mass between 180 and 220 g, more preferably between 190 g and 210
g.
[0025] Lower rotational footprint in accordance to the present
invention can be achieved for club head having volumes up to and
beyond about 460 cc, when the club head is made from multiple
materials, including one or more plastics or when discretionary
weight usable to affect changes in mass characteristics are moved
inward spaced from the perimeter of the club head, as discussed
below.
[0026] Additionally, the ratio of the MOI(y-axis) to the MOI(hosel
axis) is preferably greater than about 0.55, but is more preferably
greater than about 0.75. As shown below, this ratio can be greater
than 1.00, which indicates that MOI(hosel axis) can be made lower
than MOI(y-axis). This is another preferred embodiment of the
present invention, because it preserves the desirable high
MOI(y-axis) while minimizing the rotational foot print or MOI
(hosel axis).
[0027] Another way to control the MOI(hosel axis) is to couple the
MOI(y-axis) to the volume of the club head, since lowering the
volume of the club head is one way of lowering the MOI(hosel axis).
Preferably, the volume of the club head is greater than 350 cc, but
is more preferably between about 390 cc and about 420 cc. The ratio
of the MOI(y-axis) to the volume of the club head is preferably
greater than about 1.30 kgmm.sup.2/cm.sup.3 for a club head having
a volume of about 350 cc or greater. The ratio of the MOI(y-axis)
to the volume of the club head is more preferably greater than
about 1.45 kgmm.sup.2/cm.sup.3 and more preferably greater than
about 1.50 kgmm.sup.2/cm.sup.3 for club heads with volume of about
350 cc or greater. Preferably, this ratio is less than about 1.70
kgmm.sup.2/cm.sup.3.
[0028] Yet another way to control the MOI (hosel axis) is to limit
the distance of the center of gravity to be from about 2/3 inch to
about 1 inch measured orthogonally from hitting face. Without being
bound to any particular theory, in large or oversized driver clubs,
the center of gravity can be located more than about 1 inch from
the hitting face to provide a larger sweet spot on the hitting
face. By limiting how far back the center of gravity can be
located, i.e., from about 2/3 inch to about 1 inch from the hitting
face, one can control the volume of the club and the MOI (hosel
axis) of the club, while allowing the MOI (y-axis) to be between
450 kgmm.sup.2 and about 650 kgmm.sup.2, more preferably between
500 kgmm.sup.2 and 600 kgmm.sup.2.
[0029] The driver club of the present invention possesses
substantially similar MOI properties of the larger 460 cc driver
club but with smaller volume, and is easier for golfers to control
during the downswing.
[0030] In accordance with one aspect of the present invention, the
weight can be distributed around the club head in an inventive
manner to achieve the desirable MOI(y-axis) to MOI(hosel axis)
ratio and/or the desirable MOI(y-axis) to club head volume factor.
For objects rotating about a known axis of rotation, moment of
inertia I can be calculated using the following equation:
I=mr.sup.2
where m is the mass of the object and r is the distance of that
mass from the axis of rotation.
[0031] The MOI of a rectangular object about an axis can be
described by the equation
I= 1/12m(a.sup.2+b.sup.2)
where a is the length of the rectangle is and b is the width of the
rectangle.
[0032] When MOI must be calculated about an axis of rotation going
through a point other than the center of mass, one can determine
MOI using the parallel axis theorem. The MOI of such an object can
be calculated using the equation
I=mr.sup.2+me.sup.2
where e is the distance of the center of mass of the object from
the axis of rotation. The above equations were used to determine
MOI values of the idealized golf club heads shown in FIGS. 2, 4, 6,
8 and 10.
[0033] The golf club head of the present invention may utilize a
number of mass distribution patterns, including those shown in
FIGS. 2, 4, 6, 8 and 10, to optimize MOI(y-axis) and the MOI(hosel
axis). The mass characteristics of each idealized club head are
summarized in Table 1. The idealized club heads of FIGS. 2, 4, 6, 8
and 10 fit into the prescribed USGA-prescribed 5-inch square and
have a mass of 200 grams. For each pattern of mass distribution,
200 grams of mass were divided into two portions of the club head,
portion A and portion B. In one iteration, portion A contains
two-thirds, or 133 grams, of the mass of the club head, while
portion B contains one-third, or 67 grams, of the mass of the club
head. In a second iteration, portion A contains three-fourths, or
150 grams, of the mass of the club head, while portion B contains
one-fourth, or 50 grams, of the mass of the club head. For each
idealized club head, the y-axis runs through the geometric center
of the club head. In this illustration, mass portions A and B are
located adjacent to the perimeter of the 5inch by 5inch envelope
prescribed by the USGA. Table 1 shows MOI values about both a
y-axis running through the geometric center and the hosel axis of
an idealized golf club head. The hosel axis of the club heads shown
in FIGS. 2, 4, 6, 8 and 10 runs through point C. For FIGS. 2, 4, 6
and 8, point C is located 4 inches from toe edge 18 and 0.5 inches
from face edge 20. For FIG. 10, point C is located 4.5 inches from
toe edge 18 and 0.5 inches from face edge 20. Table 1 provides the
ratio of the MOI(y-axis) to the MOI(hosel axis) for each iteration
of mass distribution, as well as the ratio of MOI(y-axis) to volume
for each iteration of mass distribution
TABLE-US-00001 TABLE 1 MOI MOI m(club head) m(A) m(B) (y-axis)
(hosel axis) MOI(y-axis)/ MOI(y-axis)/volume [g] [g] [g] [kg
mm.sup.2] [kg mm.sup.2] MOI(hosel axis) 390 cc 420 cc 460 cc FIG. 2
200 133 67 793.69 1097.62 0.72 2.04 1.89 1.73 200 150 50 793.69
847.36 0.94 2.04 1.89 1.73 FIG. 4 200 133 67 879.41 1283.48 0.69
2.25 2.09 1.91 200 150 50 857.98 986.74 0.87 2.20 2.04 1.87 FIG. 6
200 133 67 879.50 597.06 1.47 2.26 2.09 1.91 200 150 50 858.05
471.94 1.82 2.20 2.04 1.87 FIG. 8 200 133 67 836.60 1026.12 0.82
2.15 1.99 1.82 200 150 50 825.88 793.73 1.04 2.12 1.97 1.80 FIG. 10
200 133 67 836.61 1333.58 0.63 2.15 1.99 1.82 200 150 50 825.89
1148.55 0.72 2.12 1.97 1.80
As shown in the table above, a club head fitting snugly inside a
5-inch square having a mass of 200 grams and mass distributions as
depicted in FIGS. 2, 4, 6, 8 and 10 meet the preferred ratio of
MOI(y-axis) to MOI(hosel axis). However, the calculated MOI(y-axis)
values are higher than the 590 kgmm.sup.2 USGA limit for the
idealized shapes, it is expected that for commercial club head, see
e.g., FIGS. 3, 5, 7, 9 and 11, the MOI(y-axis) would be within the
USGA limit due to the smaller footprints of the commercial club
heads. Another way to reduce the MOI (y-axis) is to reduce the mass
of areas "B" in FIGS. 2, 4, 6, 8 and 10.
[0034] Alternatively, for lower volume club heads, such as those
having volumes between 390 cc and 420 cc, mass areas "B" is moved
toward mass area "A" such that the club head fits snugly inside a
4-inch by 4-inch envelope. Point "C" would be located 3 inches from
toe edge 18 and 0.5 inch from face edge 20 for FIGS. 2, 4, 6 and 8,
and be located 3.5 inches from toe edge 18 and 0.5 inch from face
edge 20 for FIG. 10. Table 2 provides the ratio of MOI(y-axis) to
MOI(hosel axis) and the ratio of MOI(y-axis) to volume for this
configuration.
TABLE-US-00002 TABLE 2 MOI MOI M(club head) m(A) m(B) (y-axis)
(hosel axis) MOI(y-axis)/ MOI(y-axis)/volume [g] [g] [g] [kg
mm.sup.2] [kg mm.sup.2] MOI(hosel axis) 390 cc 420 cc 460 cc FIG. 2
200 133 67 430.00 665.00 0.55 1.10 1.02 0.93 200 150 50 430.74
523.45 0.82 1.10 1.03 0.94 FIG. 4 200 133 67 487.61 730.57 0.67
1.25 1.16 1.06 200 150 50 473.97 572.37 0.83 1.22 1.13 1.03 FIG. 6
200 133 67 487.61 341.63 1.43 1.25 1.16 1.06 200 150 50 473.97
280.00 1.69 1.22 1.13 1.03 FIG. 8 200 133 67 476.80 622.53 0.77
1.22 1.14 1.04 200 150 50 465.86 491.35 0.95 1.19 1.11 1.01 FIG. 10
200 133 67 505.00 926.76 0.54 1.29 1.20 1.10 200 150 50 498.59
814.74 0.61 1.28 1.19 1.08
[0035] The MOI(y-axis) values for a 4-inch by 4-inch envelope are
all under the USGA limit of 590 kgmm.sup.2. This design envelope
can be enlarged to about 4.5-inch by 4.5-inch design envelope
without exceeding the USGA limit. The ratio of MOI(y-axis) to
MOI(hosel axis) is greater than about 0.55, preferably greater than
about 0.75. Advantageously, in accordance with the present
invention, the embodiment of FIG. 6 shows that the MOI(hosel axis)
can be designed to be lower than the MOI(y-axis), i.e., the
rotational foot print can be reduced while maintaining a high MOI
(y-axis) to limit the adverse effects of off-centered hits. In
other words, the ratio of MOI(y-axis) to MOI(hosel axis) is greater
than about 1.00.
[0036] The ratio of MOI(y-axis) to club head volume for this
embodiment is from about 0.90 Kgmm.sup.2/cm.sup.3 to about 1.30
kgmm.sup.2/cm.sup.3. This ratio is preferably greater than about
0.90 Kgmm.sup.2/cm.sup.3, more preferably greater than 1.00 and
more preferably greater than about 1.10. In one example, for club
heads that can fit inside a 4.5-inch by 4.5-inch design envelope,
this ratio can be greater than about 1.20, preferably greater than
about 1.40 and more preferably greater than about 1.60. This ratio
should be less than about 1.70 kgmm.sup.2/cm.sup.3.
[0037] In accordance to another aspect of the present invention,
MOI(hosel axis) of less than about 850 kgmm.sup.2, which is
believed to be the amount of rotational mass that can be controlled
by better players or low handicapped players, while maintaining
MOI(y-axis) at more than 470 kgmm.sup.2. For higher handicapped
players, the MOI(hosel axis) should be kept to about 750 kgmm.sup.2
or less. On the other hand, the present invention allows MOI (hosel
axis), MOI (y-axis) and any of the ratios discussed herewithin to
be customized for any individual player after proper fittings.
[0038] FIGS. 3, 5, 7, 9 and 11 show driver-style club head 10
having concentrated areas of mass 12 allocated on the sole in
patterns similar to those of the idealized club heads of FIGS. 2,
4, 6, 8 and 10, respectively. A club head of the present invention
may have a pattern of mass distribution on the sole of the club
head as shown in FIGS. 3, 5, 7, 9 and 11. Concentrated areas of
mass 12 are located on the sole of golf club 10 to cause the center
of gravity of the club to remain relatively low. In order to
maximize MOI about a vertical axis running through the center of
gravity or through the geometric center of the club head, and to
minimize the MOI about the axis running through the shaft and hosel
of the club head, mass may be allocated on the sole of the club
head in regions around the base of the hosel, as shown in FIGS. 3,
5, 7 and 9. To control the location of the center of gravity, the
sole may include other concentrated areas of mass, such as toward
the back and toe as in FIGS. 3 and 5. Alternatively, other areas of
mass may be located toward the face and toe as in FIG. 7, or toward
the back as in FIG. 9. A "pseudo I-beam" pattern of mass
distribution wherein mass is concentrated toward the face edge and
toward the back, as in FIG. 11, may also be utilized.
[0039] The weight distribution data and conclusions presented above
and in Tables 1 and 2, and FIGS. 2-11 are for illustration only and
do not limit the scope of the present invention. MOI(y-axis) values
were calculated about the geometric center for ease of
illustration, since, unlike the centers of gravity, the geometric
center does not change when the masses A and B are moved around.
Furthermore, 5-inch by 5-inch square and 4-inch by 4-inch square
design envelopes are used for the illustration; however, when
smaller volume club heads are used as discussed below an
intermediate size or smaller envelope may be used. Those of
ordinary skill in the art can follow the procedure described herein
to design driver club heads that are within the scope of the
present invention.
[0040] Areas of concentrated mass, such as portions A and B of the
club heads of FIGS. 2, 4, 6, 8 and 10; areas 12 of the golf club
heads of FIGS. 3, 5, 7, 9 and 11; and other discrete portions of
mass in the golf club heads may comprises high density metals such
as stainless steel, tungsten or iron. These areas may also comprise
high density polymer composite. The material surrounding these
concentrated areas of mass preferably comprises a less dense
material, for instance metals such as aluminum, stainless steel,
magnesium or titanium, or a polymer composite with high density
fillers such as tungsten powder. Alternatively, areas of
concentrated mass may comprise the same material as that
surrounding the area of concentrated mass, however having a greater
thickness than the surrounding material.
[0041] In another embodiment of the present invention, club head 10
comprises multiple materials with a section of the club head
comprises the lightest material of the club head. The parent
application discloses a wood-type club head with weights from the
crown, sole and skirt moved aft or to the perimeter to maximize the
MOI of the club head. More specifically, the mid-section of said
club head is made from a lightweight material, such as carbon fiber
composites, thermoplastic or thermoset polymers or lightweight
metals. It had been shown in the parent application that a 460
cc/200 g club head made from titanium hitting cup, titanium aft cup
and carbon fiber tube mid-section can achieve significantly better
c.g. position and MOI properties than the same club made out of
titanium alone.
[0042] All of the multi-material club heads disclosed in the parent
case can be used in the current invention, preferably with the
volume reduced to about 390 cc-420 cc, to achieve the preferred
MOI(y-axis)/MOI(shaft axis) and MOI(y-axis)/volume ratios,
described above.
[0043] Another inventive multi-material club head is shown in FIGS.
12A-12D. FIG. 12A shows club head 30 made from three different
materials. Club head 30 comprises hitting cup 32, which includes
the hitting face, frame section 34, which includes crown and sole
bridges/connectors and crown and sole plates 36. Hitting cup 32 is
made from the material with the highest specific gravity, such as
titanium, stainless steel, magnesium. Frame 34 is made from a
material that is lighter than the material of hitting cup 32 but
heavier than the material of the crown and sole plates 36.
Preferably, frame 34 is sufficiently sturdy to provide support for
the crown and sole plates 36, and to retain the shape of club head
30. Frame 34 can be made out of aluminum, magnesium, or reinforced
or unreinforced plastic/polymer. Crown and sole plates 36 are made
from the lightest material in club head 30, such as aluminum or
reinforced or unreinforced plastic/polymer to allow more weight to
be deployed near the hitting face and the back of the club head to
achieve the preferred MOI(y-axis)/MOI(shaft axis) and
MOI(y-axis)/volume ratios.
[0044] FIGS. 12B and 12D shows club head 30 without the crown and
sole plates to more clearly show hitting cup 32 and frame 34. FIG.
12C shows the bottom view of club head 30 to illustrate more
clearly sole plates 36.
[0045] Suitable plastics/polymers for use in club head 30 include
polyetheretherketone (PEEK) commercially available as Tecapeek.TM.
from Ensinger, Inc. from Washington, Pa. Preferably, a 30% glass or
carbon reinforced PEEK, which has increased tensile strength, is
used to increase the mechanical strength of the plastic. Relevant
properties of some of the preferred materials are summarized
below.
TABLE-US-00003 Tensile Elongation Density Strength Hardness Modulus
Material (g/cc) (MPa) (Rockwell M) (GPa) Tungsten 19.3 400
Stainless Steel 7.8 210 6-4 Titanium 4.5 110 Aluminum 2.7 70 PEEK
30% 1.44 208 107 13 carbon reinforced PEEK 30% glass 1.49 157 103
9.7 reinforced PEEK 1.32 97 99 3.6
Other suitable plastics include, but are not limited to
TABLE-US-00004 Tensile Elongation Density Shore D Rockwell Strength
Modulus Plastics (g/cc) Hardness Hardness (MPa) (GPa) Acrylo-
1.02-1.2 103M 28-138 1.4-2.8 nitrile (avg. ~50) Butadiene Styrene
(ABS), impact grade, molded ABS + 10% 1.08 70 105M 43.1 3.5
cellulose fibers (CF) Polyether- 1.27 75 109M 104.9 3.1 imide (PEI)
PEI + 1.32 75-80 109M 104.9 3.1 5% CF Nylon 66 + 1.14-1.49 120R 230
2.21-17 20% CF Poly- 0.886 92R 33.1 1.31 propylene (PP)
[0046] Exemplary multi-material club heads 30 having a volume of
410 cc made from various preferred materials are illustrated
below.
TABLE-US-00005 MOI MOI Hitting Crown/Sole Mass (y-axis) (y-axis)/
cup 32 Frame 34 Plates 35 (g) kg mm.sup.2 volume Titanium Titanium
Titanium 197 416 1.01 Titanium Titanium Plastic 197 449 1.10
Titanium Aluminum Aluminum 197 456 1.11 Titanium Aluminum Platic
197 470 1.15 Titanium Plastic Plastic 197 484 1.18
As demonstrated, club head 30 made from multi-materials can achieve
significant MOI (y-axis) while retaining a smaller volume or
footprint.
[0047] According to another embodiment of the present invention,
and as shown in FIG. 13, golf club head 10 comprises an exterior
surface having a horizontal bulge radius, defined as a radius of
curvature R.sub.b, extending from heel 22 to toe 24 and measured
along the horizontal midline between the top and bottom of face 30.
Golf club head 10 further comprises a vertical roll radius, shown
in FIG. 14 and defined as a radius of curvature R.sub.r, extending
from top 26 to bottom 28 of face 30 and measured along the vertical
midline between the toe and heel edges of face 30. A golf club head
of the present invention having a MOI about the y-axis equal to or
greater than about 450 kgmm.sup.2 and less than about 500
kgmm.sup.2 preferably has a horizontal bulge radius of about 12
inches and a vertical roll radius of about 10 inches. A golf club
head having a MOI about the y-axis equal to or greater than about
500 kgmm.sup.2 and less than about 550 kgmm.sup.2 preferably has a
horizontal bulge radius of about 13 inches and a vertical roll
radius of about 10 inches. A golf club head having a MOI about the
y-axis equal to or greater than about 550 kgmm.sup.2 preferably has
a horizontal bulge radius of about 14 inches and a vertical face
roll radius of about 10 inches.
[0048] While various descriptions of the present invention are
described above, it should be understood that the various features
of each embodiment could be used alone or in any combination
thereof. Therefore, this invention is not to be limited to only the
specifically preferred embodiments depicted herein. Further, it
should be understood that variations and modifications within the
spirit and scope of the invention might occur to those skilled in
the art to which the invention pertains. Accordingly, all expedient
modifications readily attainable by one versed in the art from the
disclosure set forth herein that are within the scope and spirit of
the present invention are to be included as further embodiments of
the present invention. The scope of the present invention is
accordingly defined as set forth in the appended claims.
* * * * *